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Mattis says NATO is a "bedrock" of US policy, but insists member states must contribute their share

Trump called NATO "obsolete" in January but has softened his stance since then

(CNN)US Defense Secretary James Mattis has warned NATO that America could "moderate" its commitment to the alliance if other member states fail to meet the requisite spending targets.

Mattis reaffirmed America's support for NATO on Wednesday, describing the alliance as a "fundamental bedrock for the US and all the transatlantic community."

But speaking in Brussels, where he met with defense ministers for the first time since being sworn in, Mattis also reiterated US President Donald Trump's calls for fellow members to meet the requisite spending targets.

Only five of the 28 member states currently meet the alliance's spending target of 2% of GDP. And while Mattis stated the US was committed to NATO, he did warn that Washington would not be shy in confronting those who are failing to pull their weight financially.

James Mattis (L) speaks with members of his delegation prior to a meeting at NATO headquarters in Brussels.

"No longer can the American taxpayer carry a disproportionate share of the defense of western values," Mattis told fellow defense ministers.

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"Americans cannot care more for your children's security than you do. Disregard for military readiness demonstrates a lack of respect for ourselves, for the Alliance, and for the freedoms we inherited, which are now clearly threatened."

Mattis urged fellow ministers to put forward a plan to ensure that NATO is not in the same situation this time next year, and urged on member states to make the 2% target contributions.

He warned that the support of the US government should not be taken for granted.

"America will meet its responsibilities, but if your nations do not want to see America moderate its commitment to this alliance, each of your capitals needs to show support for our common defense."

NATO's Secretary General Jens Stoltenberg called it a "fair message" during a news conference following the American defense secretary's remarks.

"The message from Secretary Mattis is a fair message, it is a fair demand, that we need fairer burden sharing."

He noted that NATO members Latvia, Lithuania and Romania would "soon" meet the 2% spending target.

The Lithuanian defense minister, Raimundas Karoblis, indicated to CNN's Hala Gorani Wednesday that he backed Mattis's proposal to have members develop action plans and timetables for meeting the recommended defense spending levels.

"Maybe it's the way to reach this goal," he said.

Russia warning

Mattis also spoke of the need to negotiate with Russia "from a position of strength."

"We only ask that all of the NATO members make their full and proper financial contributions to the NATO alliance, which many of them have not been doing. Many of them have not been even close. And they have to do that."

Pence visit

US Vice President Mike Pence is set to meet with Stoltenberg in Brussels on February 20, when they are expected to discuss the ongoing partnership and Trump's stance on spending.

Speaking alongside Mattis, Stoltenberg said the US "has been clear that we need more defense spending, and fairer burden-sharing."

He cited figures which showed that defense spending among European allies and Canada had gone up by 3.8% in real terms in 2016, which he says is approximately $10 billion.

"This is significant, but it is not enough," he said. "We have to continue to increase defense spending across Europe and Canada. So, we need to keep the momentum."